Commit 7582b7be authored by Mike Rapoport (IBM)'s avatar Mike Rapoport (IBM) Committed by Luis Chamberlain
Browse files

kprobes: remove dependency on CONFIG_MODULES 



kprobes depended on CONFIG_MODULES because it has to allocate memory for
code.

Since code allocations are now implemented with execmem, kprobes can be
enabled in non-modular kernels.

Add #ifdef CONFIG_MODULE guards for the code dealing with kprobes inside
modules, make CONFIG_KPROBES select CONFIG_EXECMEM and drop the
dependency of CONFIG_KPROBES on CONFIG_MODULES.

Signed-off-by: default avatarMike Rapoport (IBM) <rppt@kernel.org>
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
[mcgrof: rebase in light of NEED_TASKS_RCU ]
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent 0a956d52

arch/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -60,9 +60,9 @@ config GENERIC_ENTRY 


config KPROBES

	bool "Kprobes"

	depends on MODULES

	depends on HAVE_KPROBES

	select KALLSYMS

	select EXECMEM

	select NEED_TASKS_RCU

	help

	  Kprobes allows you to trap at almost any kernel address and

include/linux/module.h

+9 −0
Original line number Diff line number Diff line
@@ -605,6 +605,11 @@ static inline bool module_is_live(struct module *mod) 
	return mod->state != MODULE_STATE_GOING;

}



static inline bool module_is_coming(struct module *mod)

{

        return mod->state == MODULE_STATE_COMING;

}



struct module *__module_text_address(unsigned long addr);

struct module *__module_address(unsigned long addr);

bool is_module_address(unsigned long addr);
@@ -857,6 +862,10 @@ void *dereference_module_function_descriptor(struct module *mod, void *ptr) 
	return ptr;

}



static inline bool module_is_coming(struct module *mod)

{

	return false;

}

#endif /* CONFIG_MODULES */



#ifdef CONFIG_SYSFS

kernel/kprobes.c

+34 −21
Original line number Diff line number Diff line
@@ -1588,7 +1588,7 @@ static int check_kprobe_address_safe(struct kprobe *p, 
	}



	/* Get module refcount and reject __init functions for loaded modules. */

	if (*probed_mod) {

	if (IS_ENABLED(CONFIG_MODULES) && *probed_mod) {

		/*

		 * We must hold a refcount of the probed module while updating

		 * its code to prohibit unexpected unloading.
@@ -1603,12 +1603,13 @@ static int check_kprobe_address_safe(struct kprobe *p, 
		 * kprobes in there.

		 */

		if (within_module_init((unsigned long)p->addr, *probed_mod) &&

		    (*probed_mod)->state != MODULE_STATE_COMING) {

		    !module_is_coming(*probed_mod)) {

			module_put(*probed_mod);

			*probed_mod = NULL;

			ret = -ENOENT;

		}

	}



out:

	preempt_enable();

	jump_label_unlock();
@@ -2488,24 +2489,6 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end) 
	return 0;

}



/* Remove all symbols in given area from kprobe blacklist */

static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)

{

	struct kprobe_blacklist_entry *ent, *n;



	list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {

		if (ent->start_addr < start || ent->start_addr >= end)

			continue;

		list_del(&ent->list);

		kfree(ent);

	}

}



static void kprobe_remove_ksym_blacklist(unsigned long entry)

{

	kprobe_remove_area_blacklist(entry, entry + 1);

}



int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,

				   char *type, char *sym)

{
@@ -2570,6 +2553,25 @@ static int __init populate_kprobe_blacklist(unsigned long *start, 
	return ret ? : arch_populate_kprobe_blacklist();

}



#ifdef CONFIG_MODULES

/* Remove all symbols in given area from kprobe blacklist */

static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)

{

	struct kprobe_blacklist_entry *ent, *n;



	list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {

		if (ent->start_addr < start || ent->start_addr >= end)

			continue;

		list_del(&ent->list);

		kfree(ent);

	}

}



static void kprobe_remove_ksym_blacklist(unsigned long entry)

{

	kprobe_remove_area_blacklist(entry, entry + 1);

}



static void add_module_kprobe_blacklist(struct module *mod)

{

	unsigned long start, end;
@@ -2672,6 +2674,17 @@ static struct notifier_block kprobe_module_nb = { 
	.priority = 0

};



static int kprobe_register_module_notifier(void)

{

	return register_module_notifier(&kprobe_module_nb);

}

#else

static int kprobe_register_module_notifier(void)

{

	return 0;

}

#endif /* CONFIG_MODULES */



void kprobe_free_init_mem(void)

{

	void *start = (void *)(&__init_begin);
@@ -2731,7 +2744,7 @@ static int __init init_kprobes(void) 
	if (!err)

		err = register_die_notifier(&kprobe_exceptions_nb);

	if (!err)

		err = register_module_notifier(&kprobe_module_nb);

		err = kprobe_register_module_notifier();



	kprobes_initialized = (err == 0);

	kprobe_sysctls_init();

kernel/trace/trace_kprobe.c

+19 −1
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk, 
	return strncmp(module_name(mod), name, len) == 0 && name[len] == ':';

}



#ifdef CONFIG_MODULES

static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)

{

	char *p;
@@ -129,6 +130,12 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) 


	return ret;

}

#else

static inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)

{

	return false;

}

#endif



static bool trace_kprobe_is_busy(struct dyn_event *ev)

{
@@ -670,6 +677,7 @@ static int register_trace_kprobe(struct trace_kprobe *tk) 
	return ret;

}



#ifdef CONFIG_MODULES

/* Module notifier call back, checking event on the module */

static int trace_kprobe_module_callback(struct notifier_block *nb,

				       unsigned long val, void *data)
@@ -704,6 +712,16 @@ static struct notifier_block trace_kprobe_module_nb = { 
	.notifier_call = trace_kprobe_module_callback,

	.priority = 1	/* Invoked after kprobe module callback */

};

static int trace_kprobe_register_module_notifier(void)

{

	return register_module_notifier(&trace_kprobe_module_nb);

}

#else

static int trace_kprobe_register_module_notifier(void)

{

	return 0;

}

#endif /* CONFIG_MODULES */



static int count_symbols(void *data, unsigned long unused)

{
@@ -1933,7 +1951,7 @@ static __init int init_kprobe_trace_early(void) 
	if (ret)

		return ret;



	if (register_module_notifier(&trace_kprobe_module_nb))

	if (trace_kprobe_register_module_notifier())

		return -EINVAL;



	return 0;